I want to sleep with my possiby bi close friend

I'm very much attracted to a coworker who used to be my former trainee (I work as a trainer). Even though he is not a direct report, the fact that I am some sort of authority figure for him makes this attraction wrong.

That's not all. He is obviously bi but he is vehemently denying it. But for some reason, the possibility that he is bi (and maybe even gay) is turning me on. He isn't flamboyant (that would turn me off), but he isn't some macho man either. He's demeanor is like Will from the TV show Will & Grace, so for me he represents a nice balance of femininity and masculinity. I've always found ruggedly handsome, truly masculine men attractive, so I find my attraction to my coworker quite baffling.

We get along really well. We have the same interests and same brand of humor, and he has quickly become my closest friend at work. This would have been great, but the problem is I'm sexually attracted to him, and I've found myself imagining having s** with him a lot lately.

A few times I thought he was flirting with me, especially the time when we both got drunk together. However, that was just my interpretation. For all I knew he was just being playful without really thinking about what he was saying.

I really am very attracted to him. I want to have wild s** with him. I don't care if he is gay or bi; this just adds to his appeal to me. I just want him to want me sexually. I know he does value me as a close female friend but that's not the only way I want him to see me. I wouldn't want him to be my serious boyfriend, but I want him to be my f*** buddy. My desire for him is leaving me so sexually frustrated. Even though I don't want to, I keep fantasizing different scenarios with which I can seduce him.